The present invention relates to an inspection system applied to a production line of electronic devices, etc., and a method for manufacturing electronic devices using such an inspection system.
More particularly, the present invention relates to an inspection system for inspecting electronic devices, which is enhanced for effective obtainment of inspection data and improvement of data analysis speed by making it easy to select and extract wafers to be inspected and analyzed, and for a method for manufacturing electronic devices, etc. using such an inspection system.
Electronic devices such as semiconductor devices are formed through repetitive treatments of wafers, which includes a plurality of processes such as photolithography, etching, etc. On the other hand, wafers treated in a predetermined process among a plurality of such manufacturing processes are inspected as needed by a particle inspection machine, a visual inspection machine, etc., and then particle information and improper shape information as to positions, sizes, quantities, types, etc. are collected. Hereafter, particle information to be detected by a particle inspection machine and improper shape information to be detected by a visual inspection machine will both be referred to as defect information generically.
As described in a monthly publication xe2x80x9cSemiconductor Worldxe2x80x9d (August, 1996, pp. 88, 99 and 102), inspection results have been transmitted from an inspection machine to an analysis unit through a network. And, the analysis unit can output any kind of analysis picture as needed, such as a trend of the total number of defects, a vertical bar graph (stack chart) for displaying the detected defect count in each defect-detected process, and/or a chart of correlation between defect count and yield, wherein the yield is calculated by using inspection results of electrical characteristics.
By using such analysis pictures, analyzers have checked and analyzed whether or not the defect count exceeds a predetermined standard, whether or not there is any abnormal defect-detected process, and whether or not there is any unique distribution of defects, and have tracked a source of various problems by using the analysis result. After that, analyzers have identified a defect-detected process and/or manufacturing equipment. Then they have tried to improve these processes and/or the manufacturing equipment to ramp up yield.
Conventionally, an object wafer, lot, or section between processes to analyze has been identified just subjectively by such analyzers, and then the identified object has been analyzed as described above.
If desired, electrical characteristics (e.g., product functional tests) of electronic devices such as semiconductor devices can be inspected for all of the wafers in a production line (100%) being processed. However, practically, defect inspections inspected by particle inspection machines or visual inspection machines are not performed on all of the wafers and are not performed in every process in order to keep the through-put of a production line up to a predetermined level.
Generally, these defect inspections are performed on some desired wafers which are processed in a desired process. Consequently, if analyzers select desired wafers and/or processes just on the basis of their subjectivity for making the above-discussed analysis pictures, they are likely to select wrong wafers that are not inspected in the desired process. If analyzers select these wrong wafers, the above-discussed analysis pictures such as trend charts and stack charts for the total number of defects cannot be calculated. Furthermore, if a selected wafer has many peculiar defects such as a cluster which is mainly caused by bad condition of the manufacturing equipment, an analysis result on the basis on these peculiar defects cannot be accepted as an analysis result of the real average capability of the manufacturing line.
For example, when yield loss impacts caused by defects are analyzed, a correlation between the defects generated in each process and the pass/fail(electrical characteristics) state of each chip on a completed wafer must be taken. In this case, the object wafers are required to be inspected in many processes, to not have any cluster data which causes analytical errors and to have a comparatively high yield to establish a correlation with defects and yield.
And furthermore, it will be very effective to make a comparison between detailed electrical characteristics (e.g., a memory fail bit map data) and a defect inspection result in order to identify a process which causes failure chips. Since this inspection process of detailed electrical characteristics is performed after an object wafer is finished, in this case, one needs to identify which wafers have been inspected consistently in the manufacturing processes.
In the case of the conventional analyzing system, however, an object wafer to be analyzed has been selected only by the subjectivity of the analyzer. Consequently, an analyzer needs to repeat selection of wafers many times until the suitable one is selected. For example, this selection might have to be repeated until a wafer that has no dense defects (cluster) appears. For that reason, the conventional analyzing system needs to spend a longer analyzing time, thereby delaying feedback of the analysis result to the manufacturing process. In addition, it is not certain whether or not the selected wafer is really a suitable one for the analysis.
In addition, even when a specific defect position is selected from data obtained in an analysis unit and observed to capture its image, it is not easy to retrieve past detected information of the wafer. It has thus been impossible to select newly found defects or defects for which images were already captured in previous processes.
When wafers are enlarged in diameter, for example, to 300xcfx86, the amount of data to be treated in the inspection process will be increased. As a result, the preparation time for analysis/inspection time will further increase.
Under such circumstances, it is an object of the present invention to make it easier to select an object wafer to be analyzed or inspected, thereby shortening the analyzing time or time for obtaining inspection data effectively.
In addition, in many conventional analyzing systems, such inspection data are retrieved and computed from a database when a user analyzes the inspection data. Some conventional analyzing systems can compute such inspection data before receiving an instruction from a user, however such systems can compute only respective analytic operations independently. Consequently, if an analysis is to be made by freely combining all the information items related to defects on a wafer, a processing time must be taken into account for each of searching and computing operations separately. As a result, a long preparation time is needed for each of such searching and computing operations. This is why it usually takes much time to feed back analyzed data to an object manufacturing process.
Under such circumstances, it is an object of the present invention to provide a system for inspecting electronic devices and a method for manufacturing electronic devices using such a system, which are enhanced for reduction of analyzing time and improvement of analyzing accuracy by solving the conventional problems and making it easier to use a large amount of defect inspection data thereby to shorten the preparing time for analysis.
In order to achieve the above object, an inspection system is provided which includes an inspection machine for inspecting a work which is processed in one of a plurality of manufacturing processes of a manufacturing line and an analysis system for outputting an inspection history list obtained by making calculations from the inspected result. The inspection history list shows a matrix of first information as to the inspection processes in which the work is inspected or the manufacturing processes corresponding to the inspection processes in which the work is inspected and second information as to the works inspected by the inspected machine.
The above inspection history list shows whether or not characteristic defects are included in the inspection result of the inspection process in which the work is inspected or the manufacturing process corresponding to the inspection process in which the work is inspected. One such characteristic defect is cluster.
The above inspection system can further include a test machine for testing the electrical characteristic of the work, wherein the inspection history list shows whether or not the electrical characteristic of the work is included.
The above inspection system can further include a plurality of the inspection machines, wherein the inspection machines can be visual inspection machines and/or particle inspection machines.
The above inspection system can further include an observation machine for capturing a defect image of the work, wherein the inspection history list shows whether or not the defect image of the work is included in the inspection result of the inspection process in which the work is inspected or the manufacturing process corresponding to the inspection process in which the work is inspected.
The above analysis system can comprise client-server system.
The above first information can further include data regarding the inspection processes in which a work is not being inspected or the manufacturing processes corresponding to the inspection processes in which a work is not being inspected.
In addition, an inspection system is provided comprising an inspection machine for inspecting a work which is processed in one of the manufacturing processes of a manufacturing line and an analysis system for creating a defect location history list for each piece of work according to inspection results obtained by the inspection machine before receiving an analysis instruction.
The above analysis system creates a defect location history list for each piece of work according to inspection results obtained by the inspection machine before receiving an analysis instruction.
The above analysis system creates the inspection history list by using the defect location history list.
In addition, an inspection system comprising an inspection machine for inspecting a work which is processed in one of the manufacturing processes of a manufacturing line and an analysis system for displaying a matrix of first information as to the inspection processes in which the work is inspected or the manufacturing processes corresponding to the inspection processes in which the work is inspected and second information as to the works inspected by the inspected machine.
In addition, an inspection system comprising an inspection machine for inspecting a work which is processed in one of the manufacturing processes of a manufacturing line and an analysis system for displaying both inspection processes in which the work is inspected and inspection processes in which the work is not inspected or both the manufacturing processes corresponding to the inspection processes in which the work is inspected and the manufacturing processes corresponding to the inspection processes in which the work is not inspected.
In addition, an analysis system comprising a storing means for storing inspection results and an outputting means for outputting an inspection history list calculated by using said stored inspection results, said inspection history list showing a matrix of first information as to the inspection processes in which the work is inspected or the manufacturing processes corresponding to the inspection processes in which the work is inspected and second information as to the works inspected by the inspected machine.
The above first information further includes the inspection processes in which a work is not inspected or the manufacturing processes corresponding to the inspection processes in which a work is not inspected.
In addition, a method for producing electrical devices comprising a processing step for processing works in a manufacturing line, an inspecting step for inspecting a work which is processed in one of the manufacturing processes of the manufacturing line by an inspection machine, an analyzing step for analyzing defects information obtained by making calculations from the inspected result, said defects information showing a matrix of the first information as to inspection processes in which the work is inspected or the manufacturing processes corresponding to the inspection processes in which the work is inspected and second information as to a plurality of the works inspected by the inspected machine and a controlling step for controlling the manufacture line on the basis of the result of the analysis.
The above defects information shows whether or not characteristic defects are included in the inspection result of the inspection process in which the work is inspected or the manufacturing process corresponding to the inspection process in which the work is inspected, said analyzing step for analyzing defects information without the characteristic defects. As an example, the above-mentioned characteristic defect can be cluster.
According to the present invention, the wafer inspection state is over viewed completely by using the inspection history list, thereby to select desired wafers to be analyzed easily. The conventional analyzers have not been able to provide such an overview. In other words, by overviewing how the wafers have been inspected so far, this make it easy to select a proper target wafer to be analyzed, thereby shortening the analyzing time and obtaining the inspection data effectively.
Furthermore, since the inspection system of the present invention is composed to be able to analyze only specific inspection results including peculiar items such as cluster and only ordinary inspection results not including peculiar items, it is possible to analyze with proper inspection result according to purpose of that analysis, thereby to improve the analyzing accuracy.
Furthermore, for example, since it is possible to select inspection processes to be excluded from an analysis object by using an inspection history list, it is easy to select the same inspection processes among the objected wafers (i.e., the wafers selected for inspection), thereby to make the conditions of counting the number of defects (added defects) detected in each inspection process even and improving the analyzing accuracy, and accordingly providing highly reliable analysis results.
Furthermore, since it is possible to select proper wafers having no cluster through all of the inspection processes and display a vertical bar graph (stack chart) as divided for each defective appearing process, which shows an average value of the generated defect counts in the processes, it is also possible to analyze the inspection results without cluster, thereby analyzing abnormalities caused by process conditions more accurately. Such clusters are mainly caused by the manufacturing equipment condition.
And, since it is possible to select proper wafers having no cluster through all of the inspection processes and display a trend of the number of added defects detected in a target process within a specified period, it is possible to analyze the inspection results without cluster, thereby detecting abnormalities caused by process conditions more accurately.
In addition, in order to achieve the above object, the analysis system of this invention can include an analysis unit for creating first information according to inspection results obtained by a plurality of inspection machines before receiving analysis instruction and for creating second information according to the first information after receiving the analysis instruction, said second information showing the inspection processes in which a work is inspected or the manufacturing process corresponding to the inspection process in which the work is inspected.
In addition, the analysis system of this invention can include a storing means for storing inspection results and an outputting means for outputting an inspection history list calculated by using said stored inspection results, said inspection history list showing first information as to the inspection processes in which a work is inspected or the manufacturing processes corresponding to the inspection processes in which a work is inspected.
In this way, the present invention enables inspection result data stored in an analysis unit for each wafer as a defect location history list. It consists of coordinates of each defect, its attribute, cluster information and captured image indexes so that all the past information items of each of the defects on a wafer can be referenced in one defect location history list. The cluster information is a result of determination of a density of defect coordinates. The attribute can include items such as quantity, size, and type of each defect detected on a wafer.
Consequently, the present invention can prearrange searching and computing operations for data analysis, so that the preparing time for analysis is reduced significantly.
The present invention has also enabled each defect location history list to be transmitted to inspection machines connected through a network.
It is thus possible now to delete all of the past defect data detected on a wafer from the current inspection data in inspection machines, so that only newly detected defects can be inspected. For example, the number of new defects generated in a manufacturing process can be known on the very inspection site, so that abnormalities detected in a manufacturing process can be fed back speedily to the manufacturing process.
In the same way, the above defect location history list can be transmitted to a defect observing unit connected through a network.
This has made it possible to observe defects to be grown through manufacturing processes, as well as defects newly generated in a manufacturing process. It is thus possible now to observe and capture defect images more effectively, since the causes of those defects are cleared.
More concretely, the system of the present invention includes a plurality of processes for treating pieces of work and a plurality of inspection machines for inspecting each piece of work treated in the processes. The system of the present invention is connected to those inspection machines via a network and further includes an analysis unit provided with at least storing means for storing inspection results obtained from the inspection machines. The system of the present invention classifies inspection data stored in the analysis unit according to the coordinates of each defect. Inspection data in a process is then processed by a cluster identifying process and a process identifying process. A cluster identifying process means a determination of the density of the defects. On the other hand, in the process identifying process, the coordinates of each detected defect are also compared with the coordinates of the defects detected in the past so as to identify each process in which each object defect is detected. After this, the processing result, the inspection process name and the defect size attached to each defect are added to the defect location history list. Consequently, the defect location history list created for each wafer is expanded in size as it goes through the manufacturing processes.
The present invention also enables a defect location history list created by the analysis terminal unit beforehand to transmit to a data analysis terminal, an inspection machine, or a defect observing machine as defect historical information of each wafer.